/Engine/Source/Runtime/CoreUObject/Public/UObject/PackageResourceManager.h
Report whether the package exists
true if the package exists, else false
bool DoesPackageExist ( const [FPackagePath](API\Runtime\CoreUObject\Misc\FPackagePath) & PackagePath, [FPackagePath](API\Runtime\CoreUObject\Misc\FPackagePath) * OutUpdatedPath )